Aluminum alloy clad material

ABSTRACT

The aluminum alloy clad material includes a core material and sacrificial materials disposed on both surfaces of the core material, the composition of the core material contains, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with a remainder consisting of Al and inevitable impurities, the composition of the sacrificial material contains, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with a remainder consisting of Al and inevitable impurities, an amount of Zn in the sacrificial material is larger than an amount of Zn in the core material by 0.2% or more, and the potential of the core material after a brazing heat treatment is within a range of −700 to −870 mV.

TECHNICAL FIELD

The present invention relates to an aluminum alloy clad material havingan excellent sacrificial anode effect.

Priority is claimed on Japanese Patent Application No. 2020-113168,filed Jun. 30, 2020, the content of which is incorporated herein byreference.

BACKGROUND ART

In recent years, there has been an increasing demand for heat exchangersfor cars that are intended for air conditioning in vehicles or thecooling of engine oil or the like. These heat exchangers need to behighly corrosion-resistant since the outside is exposed to corrosiveenvironments due to salts or dew condensation water and the coolingwater flow path of the inside is also an environment susceptible tocorrosion.

Furthermore, since heat exchangers for the vehicles need to be joined toeach of other members by a brazing heat treatment, in that use, aluminumalloy clad materials composed of a sacrificial material, a core materialand a brazing filler metal are commonly used. However, heat exchangersthat are used in such a way have a variety of forms and also may have acomplex structure, and, for example, there is a case where a fin havinga sacrificial effect is disposed to provide the anticorrosion property.

Patent Document 1 or Patent Document 2 has proposed an aluminum alloyclad material that imparts a sacrificial effect to fins.

In Patent Document 1, Mg is contained in a core material, therebyincreasing the strength. In Patent Document 2, Sn is contained in asacrificial material, thereby heightening a sacrificial anode effect.

CITATION LIST [Patent Document] [Patent Document 1]

-   Japanese Unexamined Patent Application, First Publication No.    H5-125477

[Patent Document 2]

-   Japanese Patent No. 2607245

SUMMARY OF INVENTION Technical Problem

Incidentally, in order to provide a sacrificial anticorrosion propertyto a tube by using a fin, there is a need to set the fin to a baser(lower) potential than the tube. On the other hand, when the potentialis set to be too base (low), the corrosion rate of the fin becomesexcessively fast, the fin is consumed early, and the sacrificial anodeeffect disappears.

Furthermore, in a case where a large amount of a flux is applied duringbrazing or a case where brazing is carried out by vacuum brazing, thecorrosion behavior of the fin deteriorates due to the evaporation of Znin the material during brazing, and the sacrificial anode effectdisappears due to the early consumption of the fin.

The present invention has been made in consideration of theabove-described circumstances, and an objective of the present inventionis to provide an aluminum alloy clad material enabling appropriatesacrificial anticorrosion property by setting the potential of amaterial as an appropriate value.

Solution to Problem

In a first aspect of an aluminum alloy clad material of the presentinvention, the aluminum alloy clad material includes a core material andsacrificial materials disposed on both surfaces of the core material, acomposition of the core material contains, by mass %, Mn: 0.7% to 1.8%,Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with Al balancecontaining inevitable impurities, a composition of the sacrificialmaterials contains, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3% andZn: 1.0% to 4.0% with Al balance containing inevitable impurities, anamount of Zn in the sacrificial materials is larger than an amount of Znin the core material by 0.2% or more by mass %, and the potential of thecore material after a brazing heat treatment is within a range of −700to −870 mV.

A second aspect of the aluminum alloy clad material according to theabove-described aspect, in which the potential difference between eachof the sacrificial materials and the core material is 20 to 100 mV.

A third aspect of the aluminum alloy clad material according to theabove-described aspect, in which an amount of a Mn solid solution in thecore material after the brazing heat treatment is larger than an amountof a Mn solid solution in each of the sacrificial materials by 0.2% ormore by mass %.

Advantageous Effects of Invention

According to the aluminum alloy clad material of the present invention,when the potential of a material is set as an appropriate value, afavorable sacrificial anode effect can be obtained by adjusting thepotential difference from a brazing opposite material to be anappropriate value.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing a cross section of an aluminum alloy cladmaterial of an embodiment of the present invention.

FIG. 2 is a perspective view of a heat exchanger manufactured using thealuminum alloy clad material of the embodiment of the present invention.

DESCRIPTION OF EMBODIMENT

Hereinafter, an embodiment of the present invention will be described.

An aluminum alloy clad material of the present embodiment includes acore material and sacrificial materials disposed on both surfaces of thecore material, the composition of the core material contains, by mass %,Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to3.0% with Al balance containing inevitable impurities, the compositionof the sacrificial materials contains, by mass %, Mn: 0.005% to 0.7%,Fe: 0.05% to 0.3% and Zn: 1.0% to 4.0% with Al balance containinginevitable impurities, the amount of Zn in the sacrificial materials islarger than the amount of Zn in the core material by 0.2% or more, andthe potential of the core material after a brazing heat treatment iswithin a range of −700 to −870 mV.

In addition, the potential difference between each of the sacrificialmaterials and the core material is preferably 20 to 100 mV.

In addition, the amount of the Mn solid solution in the core materialafter the brazing heat treatment is preferably larger than the amount ofthe Mn solid solution in each of the sacrificial materials by 0.2% ormore by mass %.

Hereinafter, reasons for limiting technical items that are regulated inthe present embodiment will be described. The amounts of components thatare contained in the sacrificial material and the core material areexpressed in the unit of “mass %”.

[Core Material]

Mn: 0.7% to 1.8%

Mn is an element that improves the strength. However, when the amount issmall, a desired effect cannot be sufficiently obtained, and, when Mn isexcessively contained, the manufacturability (castability androllability) is degraded. For these reasons, the amount of Mn is setwithin the above-described range. For the same reasons, it is desirablethat the lower limit of the amount of Mn is set to 0.7% and the upperlimit is set to 1.6%.

Si: 0.3% to 1.3%

Si is an element that improves the strength. However, when the amount ofSi is small, a desired effect cannot be sufficiently obtained, and, whenSi is excessively contained, the melting point decreases, and thus finsbuckle during brazing heat treatments, and the brazability deteriorates.For these reasons, in a case where Si is contained, the amount of Si isset within the above-described range. For the same reasons, it isdesirable that the lower limit is set to 0.3% and the upper limit is setto 1.1%.

Fe: 0.05% to 0.7%

Fe is an element that improves the strength. However, when the amount isexcessive, a large intermetallic compound is generated during casting,the manufacturability is degraded, and the anticorrosion property alsodeteriorates. In addition, regarding the lower limit, since an impurityis present in a raw material during casting, when the amount is set toless than the lower limit, the manufacturing cost increases. For thesereasons, the amount of Fe is set within the above-described range. Forthe same reasons, it is desirable that the lower limit is set to 0.05%and the upper limit is set to 0.4%.

Zn: 0.5% to 3.0%

Zn is contained to heighten a sacrificial anode effect. However, whenthe amount of Zn is small, a desired effect cannot be obtained, and,when the amount is excessive, the sacrificial anode effect disappearsearly due to the acceleration of the corrosion rate. For the samereasons, it is desirable that the lower limit is set to 1.0% and theupper limit is set to 2.5%.

[Sacrificial Material]

The sacrificial materials are disposed on both surface of the corematerial. The sacrificial materials on the individual surfaces may havethe same composition or may have different compositions within the rangeof the following composition.

Mn: 0.005% to 0.7%

Mn is contained to improve the strength. However, when the amount isexcessive, the manufacturability (castability and rollability) isdegraded. Furthermore, when the amount of Mn in the sacrificial materialbecomes more excessive than the amount of Mn in the core material, afterthe brazing heat treatment, there is no difference in the amount of Mnthat forms solid solutions in the sacrificial material and the corematerial, up to the core material is corroded while the sacrificialmaterial remains, and the corrosion behavior deteriorates. In addition,regarding the lower limit, since an impurity is present in a rawmaterial during casting, when the amount is set to less than the lowerlimit, the manufacturing cost increases. For these reasons, the amountof Mn is set within the above-described range. For the same reasons, itis desirable that the lower limit of the amount of Mn is set to 0.005%and the upper limit is set to 0.5%.

Fe: 0.05% to 0.3%

Fe is contained to improve the strength. However, when the amount isexcessive, a large intermetallic compound is generated during casting,which degrades the manufacturability and also degrades the anticorrosionproperty. In addition, regarding the lower limit, since an impurity ispresent in a raw material during casting, when the amount is set to lessthan the lower limit, the manufacturing cost increases. For thesereasons, the amount of Fe is determined within the above-describedrange. For the same reasons, the upper limit of the amount of Fe isdesirably set to 0.2%.

Zn: 1.0% to 4.0%

Zn heightens the sacrificial anode effect. However, when the amount istoo small, a desired effect cannot be obtained, pores are generated orup to the core material is corroded while the sacrificial materialremains, and the corrosion behavior deteriorates. On the other hand,when the amount is excessive, the sacrificial anode effect disappearsearly due to the acceleration of the corrosion rate. Furthermore, earlycorrosion of a fillet occurs. For these reasons, the amount of Zn isdetermined within the above-described range.

For the same reasons, it is desirable that the lower limit of the amountof Zn is set to 1.5% and the upper limit is set to 3.5%.

As an inevitable impurity in the sacrificial material, each of Si, Cu,Mg, Cr, Ti and the like may be contained to an extent of 0.05% or less.In addition, regarding Si, containing up to 0.1% does not make anydifference.

[Relationship Between Core Material and Sacrificial Material]

The amount of Zn in the sacrificial material is larger than the amountof Zn in the core material by 0.2% or more by mass %.

When the amount of Zn in the sacrificial material is larger than theamount of Zn in the core material by 0.2% or more, the sacrificialmaterial corrodes earlier, and the corrosion behavior of fins improves.In a case where the amount of Zn in the sacrificial material is smallerthan the amount of Zn in the core material, corrosion proceeds up to thecore material while the sacrificial material remains, and the corrosionbehavior deteriorates. The difference between the amount of Zn in thesacrificial material and the amount of Zn in the core material is morepreferably 0.5% to 2.5% and still more preferably 1.0% to 1.5%.

After the brazing heat treatment, the amount of the Mn solid solution inthe core material is preferably larger than the amount of the Mn solidsolution in the sacrificial material by 0.2% or more by mass %.

During the brazing heat treatment, since the elements in the materialsdiffuse, Zn which is added to the sacrificial material diffuses into thecore material. In such a case, the potential difference between thesacrificial material and the core material becomes small, which makes iteasy for corrosion to proceed in the sheet thickness direction. On theother hand, since Mn rarely diffuses during the brazing heat treatment,even in a case where the potential difference between the sacrificialmaterial and the core material is small, when the amount of the Mn solidsolution in the core material is set to be larger than that in thesacrificial material, the potential difference near the interfacebetween the sacrificial material and the core material becomes large,the sacrificial material corrodes earlier, and the corrosion behavior offins improves. For the above-described reasons, the amount of the Mnsolid solution is determined within the above-described range.

The amount of the Mn solid solution in the core material after thebrazing heat treatment is preferably larger than the amount of the Mnsolid solution in the sacrificial material by 0.3% or more.

As the brazing heat treatment, as an example, the aluminum alloy cladmaterial is heated up to 600° C. from room temperature (5° C. to 40° C.)for 20 minutes and held at 600° C. for three minutes. This will also betrue below. However, as the present embodiment, the brazing conditionsare not limited to the above description.

[Potential]

The potential of the core material after the brazing heat treatment iswithin a range of −720 mV to −870 mV.

When the core material has a predetermined potential, the sacrificialanode effect can be obtained. When the potential is too high, a desiredeffect cannot be obtained, and, when the potential is too low, thesacrificial anode effect disappears early due to the acceleration of thecorrosion rate.

The potential of the core material after the brazing heat treatment ispreferably within a range of −730 mV to −870 mV and more preferablywithin a range of −770 mV to −840 mV.

The potential difference between the sacrificial material and the corematerial (core material potential−sacrificial material potential) ispreferably 20 mV to 100 mV.

When the potential difference is within the above-described range, thecorrosion behavior of fins improves. When the potential difference istoo small, the core material also corrodes while the sacrificialmaterial remains, and the corrosion behavior deteriorates. When thepotential difference is excessive, the sacrificial anode effectdisappears early due to the acceleration of the corrosion rate.

The potential difference between the sacrificial material and the corematerial is more preferably in a range of 40 mV to 100 mV.

Hereinafter, an example of a method for manufacturing the aluminum alloyclad material of the present embodiment will be described.

An aluminum alloy for the core material and an aluminum alloy for thesacrificial material each having the composition of the presentembodiment are prepared. These alloys can be manufactured by a normalmethod, and the manufacturing method is not particularly limited. Forexample, the alloys can be manufactured by the semi-continuous casting.

As the aluminum alloy for the core material, an alloy having acomposition containing, by mass %, Mn: 0.7% to 1.8%, Si: 0.3% to 1.3%,Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0% with Al balance containinginevitable impurities is used.

As the aluminum alloy for the sacrificial material, an alloy having acomposition containing, by mass %, Mn: 0.005% to 0.7%, Fe: 0.05% to 0.3%and Zn: 1.0% to 4.0% with Al balance containing inevitable impurities isused.

Regarding the selection of the compositions, the compositions aredesirably set such that the amount of Zn in the sacrificial material islarger than the amount of Zn in the core material by 0.2% or more bymass %.

After the aluminum alloy for the core material or the aluminum alloy forthe sacrificial material is melted, a homogenization treatment can becarried out as desired.

In the homogenization treatment, Mn that has formed a solid solution inthe supersaturation state in the matrix during casting is precipitatedas an intermetallic compound. Since the size or dispersion amount of theintermetallic compound that is precipitated is affected by thetemperature and time of the homogenization treatment, it is necessary toselect appropriate heat treatment conditions.

Ordinarily, when the heat treatment is carried out at a hightemperature, the precipitation and growth of the intermetallic compoundare accelerated, and the Mn solid solubility becomes low. Conversely,when the heat treatment is carried out at a low temperature, theprecipitation and growth of the intermetallic compound are suppressed,and the Mn solid solubility becomes high. In addition, when theintermetallic compound that is precipitated by the homogenizationtreatment is refined, the precipitate is melted again by the brazingheat treatment and forms a solid solution in the materials, and thus theamount of the Mn solid solution after the brazing heat treatmentincreases.

On the other hand, when the intermetallic compound that is precipitatedby the homogenization treatment is coarsened, during the brazing heattreatment, the compound is partially melted, but not completely melted,and thus the amount of the Mn solid solution after the brazing heattreatment decreases.

In the present embodiment, since the corrosion behavior of fins isimproved by setting the amount of the Mn solid solution in the corematerial to be larger than the amount of the Mn solid solution in thesacrificial material by 0.2% or more by mass %, it is necessary tocontrol the amount of the Mn solid solution by appropriately combiningthe homogenization treatment or the hot rolling and annealingtemperature conditions.

In the present embodiment, since the corrosion behavior of fin materialsis improved by the difference in the amount of the Mn solid solutionbetween the core material and the sacrificial material, thehomogenization treatment is carried out on the core material at 400° C.to 500° C. for four to 16 hours, and a precipitate is finelyprecipitated. On the other hand, on the sacrificial material, basically,the homogenization treatment is not carried out; however, when thehomogenization treatment is carried out at 500° C. to 600° C., which isa higher temperature than that for the core material, for four to 16hours, and a precipitate in the sacrificial material is coarsenedcompared with that in the core material, the amount of Mn that forms asolid solution in the sacrificial material is decreased, and thecorrosion behavior is improved.

The aluminum alloy for the core material or the aluminum alloy for thesacrificial material are made into sheet materials by hot rolling. Inaddition, the aluminum alloys may also be made into sheet materials bycontinuous casting rolling.

In the hot rolling, it is possible to set the finishing temperature.

Usually, hot rolling is loaded at a high temperature of approximately500° C., and, after the hot rolling, the sheet materials are coiled andcooled to room temperature.

In this case, since the time during which the aluminum alloys are heldat high temperature changes depending on the finishing temperature ofthe hot rolling, the finishing temperature has an influence on theprecipitation behaviors of the intermetallic compound.

The sheet materials are hot-rolled and then further cold-rolled, wherebyan aluminum alloy clad material having a desired thickness can beobtained.

As the present embodiment, the cladding rate in the clad material is notparticularly limited, but 5% to 25% of the thickness of the sacrificialmaterial on one surface, 50% to 90% of the core material thickness andthe like are used.

In the above description, the sacrificial material has been described tobe directly laminated on the core material, but may be laminated througha different layer.

The clad material is set to a thickness of, for example, 0.05 to 0.20 mmby cold rolling. In the middle of the cold rolling, intermediateannealing may be carried out.

The conditions for the intermediate annealing can be selected from, forexample, ranges of 150° C. to 400° C. and one to 10 hours. However, whenthe intermediate annealing temperature becomes a high temperature, theprecipitation and growth of the intermetallic compound are acceleratedduring the annealing, and the difference in the amount of the Mn solidsolution between the sacrificial material and the core material becomessmall, and thus the intermediate annealing is desirably carried out at atemperature of 300° C. or lower.

These sheet materials are disposed and laminated such that a sacrificialmaterial 3 a is disposed on one surface of a core material 2 and asacrificial material 3 b is disposed on the other surface as shown inFIG. 1 , and the laminated materials are cladded at appropriate claddingrates in the above-described state, whereby an aluminum alloy cladmaterial 1 is produced. The sacrificial materials 3 a and 3 b may havethe same composition or may have different compositions within the rangeof the above-described composition.

The obtained clad material can be used as, for example, a tube materialfor a heat exchanger, a fin and the like. The sacrificial material 3 aor 3 b and the core material 2 have a potential difference of 20 mV to100 mV.

A fin material for a heat exchanger is joined by brazing to anappropriate member to be brazed such as a tube.

As the present embodiment, the material, shape and the like of themember to be brazed are not particularly limited, and an appropriatealuminum material can be used.

The heat treatment conditions during brazing are not particularlylimited except that the fin material and the member to be brazed areheated up to 590° C. to 615° C., and it is possible to carry out thebrazing under conditions under which, for example, the fin material andthe member to be brazed are heated at a heating rate at which the timetaken for the temperature to reach the target temperature from 550° C.becomes one minute to 10 minutes, held at the target temperature of 590°C. to 615° C. for one minute to 20 minutes, then, cooled to 300° C. at50 to 100° C./min and then cooled to room temperature in the air. Theamount of the Mn solid solution in the core material desirably becomeslarger than the amount of the Mn solid solution in the sacrificialmaterial by 0.2% or more by mass % after the brazing heat treatment.

In addition, after the brazing, the potential of the core material iswithin a range of −720 to −870 mV.

In the core material of the member to be brazed, which is a member toprovide the anticorrosion property, only the potential of the corematerial is regulated, in consideration of ordinarily-used Al—Mn-basedalloys.

The potential is prepared depending on the compositions of the materialsand the manufacturing conditions.

FIG. 2 shows a heat exchanger for an aluminum vehicle 4 for which fins 5are formed using the aluminum alloy clad material and aluminum alloytubes 6 are used as a member to be brazed. The fins 5 and the tubes 6are combined with a reinforcing material 7 and a header plate 8 andbrazed to obtain the heat exchanger for an aluminum vehicle 4.

Examples

Aluminum alloys for sacrificial materials and core materials were castby semi-continuous casting based on compositions (the remainder was A1and inevitable impurities) shown in Table 1 and Table 2. As the aluminumalloys for sacrificial materials and core materials, alloys having acomposition (the remainder was A1 and inevitable impurities) shown inTable 1 and Table 2 were used. The sacrificial materials contained Si inthe compositions shown in Table 1 and Table 2 as an inevitable impurity.Next, homogenization treatments were carried out under conditions shownin Table 3 and Table 4, hot rolling and cold rolling were carried out,then, intermediate annealing was carried out, and sheet materials wererolled up to a sheet thickness of 0.2 mm by cold rolling, therebyproducing Temper H14 sheet materials (clad materials). The cladmaterials were produced such that the cladding rate of the sacrificialmaterial on one surface became 10%.

On test materials from the obtained clad materials of Examples 1 to 33and Comparative Examples 1 to 16, the following evaluation methods werecarried out. Individual evaluation results are shown in Table 3 andTable 4.

[Corrosion Evaluation of Test Material]

A brazing heat treatment was carried out on the test material having asheet thickness of 0.20 mm after final rolling, and the test materialwas used as a material that was to be subjected to a corrosion test.

[Evaluation of Sacrificial Anticorrosion Property]

The test material having a sheet thickness of 0.20 mm, which wascorrugated, was combined to a brazing filler metal surface of a brazingsheet having a sheet thickness of 0.3 mm (cladding configuration:brazing filler metal (10%)/core material (75%)/sacrificial material(15%), brazing filler metal: JIS A 4045 alloy, core material:Al-1.OMn-0.5Cu alloy, sacrificial material: JIS A 7072 alloy), and abrazing heat treatment was carried out.

As the brazing conditions, a brazing-equivalent heat treatment in whicha sample of the test material to which 10 g/m² of K₁₋₃AlF₄₋₆ had beenapplied as a flux was heated up to 600° C. from room temperature (20°C.) in a high-purity nitrogen gas atmosphere for 20 minutes, held at600° C. for three minutes and then cooled to 300° C. at 60° C./minutewas carried out.

After that, a sacrificial material surface of the test material wasmasked, and an immersion test was carried out using OY water (Cl⁻: 195ppm, SO₄ ²⁻: 60 ppm, Cu²⁺: 1 ppm, Fe³⁺: 30 ppm remainder pure water) ina state where the test material and the brazing filler metal surface ofthe brazing sheet were exposed. As the test conditions, room temperature(20° C.)×16 h+88° C.×8 h (no stirring) was regarded as a one-day cycle,and the test material and the brazing sheet were immersed for two weeksin the corrosion evaluation of a fin and for eight weeks in theevaluation of sacrificial anticorrosion property. After that, acorrosion product was removed with chromium acid phosphate, and thecorrosion behavior of the test material and the depth of a corroded partof the brazing sheet were evaluated.

[Corrosion Evaluation Standards of Test Material]

D: Early corrosion of the core material occurs (core material: only thesheet thickness center part corrodes earlier).

C: Partial pitting corrosion is observed (a part of the sacrificialmaterial is left undissolved, and the core material corrodes).

B: The majority is surface corrosion, but extremely partial pittingcorrosion is observed.

A: The whole surface is surface corrosion.

[Evaluation Standards of Sacrificial Anticorrosion Property]

D: A through hole is generated in the brazing sheet.

C: The depth of corrosion occurring in the brazing sheet is half of thesheet thickness (0.125 mm) or more and less than penetration.

B: The depth of corrosion occurring in the brazing sheet is less thanhalf of the sheet thickness (0.125 mm).

A: The depth of corrosion occurring in the brazing sheet is less than ¼of the sheet thickness (0.06 mm).

[Measurement of Natural Potential]

The natural potentials of a core material and a sacrificial material inthe fin were measured using a silver/silver chloride electrode in asolution obtained by adjusting the pH of a 5% NaCl solution to 3.0 withacetic acid.

[Evaluation of Strength after Brazing Heat Treatment]

A material after a brazing-equivalent heat treatment was milled to a JISNo. 5 test piece shape, and the strength was measured by a tensile test.

[Evaluation Standards of Strength after Brazing Heat Treatment]

D: The tensile strength after the brazing heat treatment is less than 90MPa.

C: The tensile strength after the brazing heat treatment is 90 MPa ormore and less than 120 MPa.

B: The tensile strength after the brazing heat treatment is 120 MPa ormore.

[Measurement of Mn Solid Solubility]

A fin material after a brazing heat treatment was etched with a 10% NaOHsolution, and a sample only composed of a core material and asacrificial material was produced. After that, the core material and thesacrificial material were each dissolved by the thermal phenol method,and the obtained solution was subjected to ICP emission spectroscopicanalysis, thereby measuring the solid solubility amount of Mn.

TABLE 1 Difference in the amount of Zn between sacrificial Potential ofAlloy composition of sacrificial material Alloy composition of corematerial material and core material core material Test (mass %) (mass %)(mass %) (* sacrificial after brazing material No. Mn Si Fe Zn Mn Si FeZn material − core material) (mV) Example 1 0.005 0.02 0.1 2.0 1.0 0.70.3 1.5 0.5 −775 2 0.5 0.02 0.2 1.5 1.0 0.7 0.3 1.0 0.5 −730 3 0.5 0.030.2 1.5 1.0 0.7 0.3 1.2 0.3 −730 4 0.5 0.01 0.2 1.7 1.0 0.7 0.3 1.2 0.5−730 5 0.005 0.02 0.1 3.5 1.0 0.5 0.4 2.0 1.5 −820 6 0.005 0.01 0.1 2.50.7 0.5 0.4 1.0 1.5 −765 7 0.005 0.02 0.1 2.5 0.7 1.0 0.4 1.0 1.5 −750 80.005 0.03 0.05 2.5 0.7 1.0 0.4 1.0 1.5 −745 9 0.005 0.02 0.05 2.5 1.00.3 0.4 1.0 1.5 −760 10 0.005 0.01 0.1 2.5 1.2 0.3 0.4 1.0 1.5 −755 110.005 0.01 0.1 2.5 0.7 0.3 0.1 1.0 1.5 −770 12 0.005 0.02 0.1 2.5 0.70.3 0.2 1.5 1.0 −790 13 0.005 0.01 0.1 2.5 0.7 0.3 0.2 1.5 1.0 −800 140.005 0.01 0.1 2.5 0.7 0.3 0.2 2.0 0.5 −840 15 0.005 0.02 0.1 3.5 0.70.3 0.2 3.0 0.5 −870 16 0.005 0.04 0.1 2.0 1.8 1.3 0.7 0.5 1.5 −710 170.005 0.03 0.1 2.0 1.8 1.3 0.7 1.0 1.0 −730 18 0.005 0.01 0.1 1.5 1.81.3 0.7 1.0 0.5 −730 19 0.005 0.01 0.1 1.5 1.8 1.3 0.7 1.0 0.5 −710 200.5 0.04 0.3 2.0 1.8 1.3 0.7 1.0 1.0 −730 21 0.005 0.03 0.1 4.0 1.8 1.30.7 3.0 1.0 −850 22 0.005 0.02 0.1 2.5 1.8 0.7 0.4 1.0 1.5 −760 23 0.70.04 0.3 2.0 1.2 0.7 0.3 1.5 0.5 −770 24 0.7 0.04 0.3 2.0 1.0 0.5 0.31.5 0.5 −765 25 0.005 0.01 0.1 1.0 1.0 0.5 0.4 0.5 0.5 −725

TABLE 2 Difference in the amount of Zn between sacrificial Potential ofAlloy composition of sacrificial material Alloy composition of corematerial material and core material core material Test (mass %) (mass %)(mass %) (* sacrificial after brazing material No. Mn Si Fe Zn Mn Si FeZn material − core material) (mV) Example 26 0.005 0.04 0.1 1.0 0.7 0.30.1 0.7 0.3 −725 27 0.005 0.02 0.1 1.0 1.6 1.0 0.4 0.5 0.5 −710 28 0.0050.04 0.1 4.0 1.0 0.5 0.4 1.5 2.5 −765 29 0.7 0.04 0.3 4.0 1.0 0.5 0.41.5 2.5 −765 30 0.7 0.04 0.3 2.5 1.6 1.0 0.4 1.5 1.0 −760 31 0.7 0.040.3 2.5 1.2 0.5 0.4 1.5 1.0 −765 32 0.7 0.02 0.3 2.0 1.2 0.7 0.3 1.5 0.5−770 33 0.7 0.04 0.3 2.0 1.2 0.7 0.3 1.5 0.5 −770 Comparative 1 Nosacrificial material 1.0 0.7 0.3 1.5 — −775 Example 2 0.7 0.04 0.3 0.50.7 0.7 0.4 1.0 −0.5  −750 3 0.005 0.02 0.1 2.0 2.5 1.0 0.4 1.5 Materialproduction is impossible due to rupture during rolling 4 0.005 0.02 0.12.0 1.2 2.0 0.4 1.5 Evaluation is impossible due to fin buckling duringbrazing 5 0.005 0.01 0.1 2.0 1.6 1.0 1.0 1.5 Material production isimpossible due to rupture during rolling 6 1.0 0.03 0.3 1.5 0.7 0.3 0.31.0 0.5 −780 7 0.1 0.04 1.0 2.0 1.2 0.7 0.3 1.5 Material production isimpossible due to rupture during rolling 8 0.005 0.01 0.2 1.0 1.6 0.70.4 0.0 1.0 −680 9 0.005 0.01 0.2 2.0 1.6 0.7 0.4 0.0 2.0 −680 10 0.0050.02 0.2 3.0 1.6 0.7 0.4 0.0 3.0 −680 11 0.005 0.01 0.2 2.0 1.6 0.7 0.40.3 1.7 −690 12 0.005 0.03 0.2 4.5 1.6 0.7 0.4 4.0 0.5 −850 13 0.0050.04 0.2 1.0 0.7 0.3 0.3 4.0 −3.0  −900 14 0.005 0.04 0.1 2.0 0.3 0.30.4 1.0 1.0 −775 15 0.005 0.02 0.1 2.0 0.7 0.1 0.4 1.0 1.0 −760 16 0.0050.02 0.1 2.0 0.5 0.1 0.2 1.0 1.0 −770

TABLE 3 Difference in the amount of Potential Mn solid solu- differencetion between between core Homogeniza- core material material andHomogeniza- tion treatment Inter- and sacrifi- sacrificial tiontreatment conditions of mediate cial material material StrengthEvaluation Evaluation conditions of sacrificial annealing after brazingafter brazing after of strength of core material material conditions(mass %) (* (mV) (* core brazing after Corrosion sacrificial Test(temperature: (temperature: (temperature: core material − material −heat brazing Evaluation anti- material ° C., time: ° C., time: ° C.,time: sacrificial sacrificial treatment heat of Test corrosion No. hour)hour) hour) material) material) (MPa) treatment Material propertyExample 1 450° C., 10 h — 300° C., 4 h 0.3 65 112 C A A 2 550° C., 4 h — 400° C., 3 h 0.1 40 106 C B A 3 400° C., 10 h — 200° C., 7 h 0.3 40110 C A A 4 400° C., 10 h 580° C., 4 h 200° C., 7 h 0.5 40 109 C A A 5450° C., 10 h — 300° C., 4 h 0.3 80 105 C A A 6 400° C., 10 h — 200° C.,7 h 0.3 125 100 C A B 7 400° C., 10 h — 200° C., 7 h 0.2 140 120 B A B 8400° C., 10 h — 400° C., 3 h 0.1 145 118 B B B 9 400° C., 10 h — 200°C., 7 h 0.4 130 101 C A B 10 400° C., 10 h — 200° C., 7 h 0.5 135 106 CA B 11 400° C., 10 h — 200° C., 7 h 0.3 120 92 C A B 12 400° C., 10 h —200° C., 7 h 0.3 90 96 C A A 13 500° C., 6 h  — 400° C., 3 h 0.2 80 90 CA A 14 450° C., 10 h — 300° C., 4 h 0.3 50 94 C A A 15 500° C., 6 h  —400° C., 3 h 0.2 10 92 C B C 16 500° C., 6 h  — 300° C., 4 h 0.5 130 145B B C 17 500° C., 6 h  — 300° C., 4 h 0.5 110 142 B A B 18 500° C., 6 h — 330° C., 4 h 0.5 90 144 B A A 19 400° C., 10 h — 200° C., 7 h 0.8 110151 B A B 20 500° C., 6 h  — 270° C., 4 h 0.5 40 153 B A A 21 500° C., 6h  — 270° C., 4 h 0.5 40 144 B A A 22 500° C., 6 h  — 300° C., 4 h 0.6120 130 B A B 23 450° C., 10 h 550° C., 4 h 200° C., 7 h 0.2 40 121 B AA 24 550° C., 4 h  — 400° C., 3 h 0.1 15 121 B C A 25 450° C., 10 h —300° C., 4 h 0.3 90 108 C A A

TABLE 4 Difference in the amount of Potential Mn solid solu- differencetion between between core Homogeniza- core material material andHomogeniza- tion treatment Inter- and sacrifi- sacrificial tiontreatment conditions of mediate cial material material StrengthEvaluation Evaluation conditions of sacrificial annealing after brazingafter brazing after of strength of core material material conditions(mass %) (* (mV) (* core brazing after Corrosion sacrificial Test(temperature: (temperature: (temperature: core material − material −heat brazing Evaluation anti- material ° C., time: ° C., time: ° C.,time: sacrificial sacrificial treatment heat of Test corrosion No. hour)hour) hour) material) material) (MPa) treatment Material propertyExample 26 400° C., 10 h — 200° C., 7 h 0.2 90 93 C A A 27 500° C., 6 h — 300° C., 4 h 0.4 110 138 B A B 28 450° C., 10 h — 270° C., 4 h 0.3 135108 C A B 29 450° C., 10 h 580° C., 4 h 270° C., 4 h 0.2 85 110 C A A 30450° C., 10 h 580° C., 4 h 270° C., 4 h 0.4 40 142 B A A 31 400° C., 10h 580° C., 4 h 200° C., 7 h 0.4 35 118 C A A 32 550° C., 4 h  — 300° C.,4 h 0.1 10 117 C C A 33 450° C., 10 h 580° C., 4 h 330° C., 4 h 0.3 25123 B A A Comparative 1 450° C., 10 h — 400° C., 3 h — — 125 B D CExample 2 450° C., 10 h — 400° C., 3 h 0.1 −5 115 C D C 3 Materialproduction is impossible due to rupture during rolling 4 Evaluation isimpossible due to fin buckling during brazing 5 Material production isimpossible due to rupture during rolling 6 550° C., 4 h  — 400° C., 3 h−0.3  10 85 D D C 7 Material production is impossible due to ruptureduring rolling 8 500° C., 6 h  — 400° C., 3 h 0.3 50 118 C C D 9 500°C., 6 h  — 400° C., 3 h 0.3 130 121 B B D 10 500° C., 6 h  — 400° C., 3h 0.3 140 119 C B D 11 500° C., 6 h  — 400° C., 3 h 0.3 110 123 B B D 12500° C., 6 h  — 400° C., 3 h 0.3 50 119 C B D 13 450° C., 10 h — 400°C., 3 h 0.2 −20 93 C D D 14 500° C., 6 h  — 330° C., 4 h 0.1 65 85 D B B15 450° C., 10 h — 200° C., 7 h 0.3 80 85 D A A 16 550° C., 4 h  — 400°C., 3 h 0.1 70 80 D B B

In the present examples, the combination of the fin, which correspondsto the clad material of the present invention, and a tube, which is anopposite material, was assumed, and it was clarified that thesacrificial anticorrosion property is provided to the tube and the earlyconsumption of the fin is suppressed by enabling the setting of thepotential of the fin with respect to the potential of the tube within anappropriate range. In addition, the sacrificial materials are impartedon both surfaces of the fin, and the potentials of the core material andthe sacrificial material in the fin are also set within appropriateranges, whereby an effect of suppressing corrosion in the sheetthickness direction caused by the early corrosion of the sacrificialmaterial and improving the corrosion behavior is created.

In the present specification, the outer fin was typically used in thedescription of the objective and the effect, but the present inventionis not limited to the outer fin, and the same effect can also beobtained in fins other than the outer fin or other uses.

Hitherto, the present invention has been described based on theembodiment and the examples, but the present invention is not limited tothe contents of these descriptions, and appropriate modification of theembodiment is possible within the scope of the present invention.

REFERENCE SIGNS LIST

-   -   1 Clad material    -   2 Core material    -   3 a Sacrificial material    -   3 b Sacrificial material    -   4 Heat exchanger    -   5 Fin    -   6 Tube

1. An aluminum alloy clad material, comprising: a core material; andsacrificial materials disposed on both surfaces of the core material;wherein; a composition of the core material comprises, by mass %, Mn:0.7% to 1.8%, Si: 0.3% to 1.3%, Fe: 0.05% to 0.7% and Zn: 0.5% to 3.0%with an Al balance containing inevitable impurities; a composition ofthe sacrificial materials comprises, by mass %, Mn: 0.005% to 0.7%, Fe:0.05% to 0.3% and Zn: 1.0% to 4.0% with an Al balance containinginevitable impurities; an amount of Zn in the sacrificial materials islarger than an amount of Zn in the core material by 0.2% or more by mass%; and a potential of the core material after a brazing heat treatmentis within a range of −700 to −870 mV.
 2. The aluminum alloy cladmaterial according to claim 1, wherein a potential difference betweeneach of the sacrificial materials and the core material (a core materialpotential—a sacrificial material potential) is 20 to 100 mV after thebrazing heat treatment.
 3. The aluminum alloy clad material according toclaim 1, wherein an amount of a Mn solid solution in the core materialafter the brazing heat treatment is larger than an amount of a Mn solidsolution in each of the sacrificial materials by 0.2% or more by mass %.4. The aluminum alloy clad material according to claim 2, wherein anamount of a Mn solid solution in the core material after the brazingheat treatment is larger than an amount of a Mn solid solution in eachof the sacrificial materials by 0.2% or more by mass %.